Effects of diuretics on GABA‐gated chloride current in frog isolated sensory neurones

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Abstract
1 Effects of three diuretics (furosemide, amiloride and α-human atrial natriuretic polypeptide (α-hANP)) on GABA-activated chloride current (ICl) were investigated in frog isolated sensory neurones, following suppression of Na+, K+ and Ca2+ currents, by use of a ‘concentration-clamp’ technique. 2 Furosemide inhibited the GABA-activated ICl in a non-competitive manner and facilitated the inactivation phase, while amiloride inhibited the GABA response in a competitive manner, both inhibitions being concentration-dependent. α-hANP had no effects on the GABA-induced ICl. 3 The reversal potential of GABA-activated ICl (EGABA) was not shifted in the presence of amiloride or furosemide. 4 The results suggest that amiloride may act at the GABA binding site while furosemide may act on the GABA-gated chloride channel.